1. Field of the Invention
The present invention relates to transformers, loudspeaker devices, loudspeaker networks, and loudspeaker systems, and more specifically relates to a transformer included in a piezoelectric loudspeaker, and to a loudspeaker device, a loudspeaker network, and a loudspeaker system that include the above-described transformer.
2. Description of the Related Art
A transformer for a conventional piezoelectric loudspeaker is constructed such that a primary winding and a secondary winding are wound around a bobbin and a core is inserted into the bobbin.
In the above-described transformer for the conventional piezoelectric loudspeaker, the transformer is expensive as well as heavy due to the use of the core. Accordingly, the removal of the core has been contemplated to produce an inexpensive and light-weight transformer. However, the removal of the core decreases the magnetic coupling strength between the primary winding and the secondary winding. Moreover, to reduce the size of the piezoelectric loudspeaker, it is desirable to provide another member, such as a portion of the loudspeaker, within the above-described transformer of the conventional piezoelectric loudspeaker. These points also apply to a loudspeaker device, a loudspeaker network, and a loudspeaker system that include the transformer for the conventional piezoelectric loudspeaker.
In order to overcome the problems described above, preferred embodiments of the present invention provide an inexpensive, compact, and lightweight transformer which has strong magnetic coupling between a primary winding and a secondary winding, and which can hold another member therein.
Further, preferred embodiments of the present invention provide a loudspeaker device, a loudspeaker network, and a loudspeaker system which include a transformer that is inexpensive, compact, and lightweight, and that has strong magnetic coupling between a primary winding and a secondary winding, and which has another member disposed therein.
According to a first preferred embodiment of the present invention, a transformer including a bobbin having a cavity, a primary winding wound around the bobbin, and a secondary winding wound around the bobbin and magnetically coupled with the primary winding is provided. In the transformer, at least one of the primary winding and the secondary winding is divided into at least two portions which include a portion wound at the inside and a portion wound at the outside, at least a portion of the other one of the primary winding and the secondary winding is wound between said at least two portions obtained by dividing the one of the primary winding and the secondary winding, and at least a portion of the cavity of the bobbin is used as a space to accommodate another member therein.
According to another preferred embodiment of the present invention, a loudspeaker device includes a transformer as described in the previous paragraph, and a loudspeaker, connected to the transformer, and including a sound-producing body having a piezoelectric body. In the loudspeaker device, at least a portion of the loudspeaker is provided in the cavity of the bobbin.
In the loudspeaker device according to another preferred embodiment of the present invention, the loudspeaker has a horn for conducting sound waves transmitted from the sound-producing body, one end of the horn is inserted into the cavity of the bobbin, and the bobbin of the transformer is mounted on the horn.
According to another preferred embodiment of the present invention, a loudspeaker network includes a transformer having the features of the preferred embodiment described above and an impedance network connected to the transformer.
According to a further preferred embodiment of the present invention, a loudspeaker system includes a loudspeaker device according to a preferred embodiment described above, and a loudspeaker network according to the preferred embodiment described above. In the loudspeaker device, the transformer of the loudspeaker device includes the transformer of the loudspeaker network.
Since there is no core used in the transformer, the transformer is inexpensive as well as lightweight.
Furthermore, in the transformer according to preferred embodiments of the present invention, since at least one of the primary winding and the secondary winding is wound between at least two portions obtained by dividing the other one of the primary winding and the secondary winding, the magnetic coupling between the primary winding and the secondary winding of the transformer is stronger than a transformer constructed by winding the entire primary winding and the winding the entire secondary.
Also, in the transformer according to preferred embodiments of the present invention, since a portion of the cavity of the bobbin is used as a space for having another member disposed therein, another member, such as an end portion of the horn of the loudspeaker, can be disposed therein.